The present invention relates to reading apparatus for reading optically readable information such as a bar code or characters printed on a record medium such as a label or the like.
As general background art, reference may be made to U.S. Pat. Nos. 4,408,120, 4,488,678, 4,516,017, 4,528,444 and 4,538,060 and the U.S. patent application Ser. No. 693,825 of Hara et al filed Jan. 23, 1985 and now abandoned.
Conventional apparatus of this type is disclosed in a Japanese patent application having a laid-open patent No. 60-171581 published Sept. 5, 1985. That patent application discloses information reading apparatus in which illuminating means illuminates a label on which optically readable information such as a bar code or characters is printed so that an image of the information in light reflected therefrom is imaged onto a reading sensor for converting the image into an electric signal by an electronic scanning operation.
In this kind of conventional apparatus, however, it is difficult to determine what part of the label is scanned or whether the apparatus is operating in focus. This results in not being able to read the information correctly. For example, in a case where a line to be scanned on the label is not illuminated enough by illuminating means when an opening of a handheld reader faces the label, or where optical means and the reading sensor for imaging the optical information are out of focus, the optically readable information can not be read correctly.